1. Field of the Invention
The present invention relates to fluid distribution manifold, and more particularly to manifolds suitable for use in automated chemical processing instruments.
2. Description of Related Art
In the past, fluid distribution manifolds typically consisted of a plenum made up of at least two major structural components that were usually assembled with a number of fasteners each requiring either a separate gasket or sealant. Fluid conduits were typically connected to the plenum, i.e. to one or both of the structural components, using some type of commercial fitting at each connection. While the commonality of such commercial fittings might result in relatively low component cost, the labor cost required to implement their use and assemble a manifold with a large number of conduits can be quite high. For manifolds to be used with small diameter conduits, it required additional effort to assemble the smaller components and to ensure that the appropriate torque is applied to each fitting. When the number of fittings increases, it becomes more difficult to ensure that all of the fittings are properly assembled.
Where a manifold is implemented in a chemical processing instrument for the purpose of pressurizing containers of different chemical reagents using a single fluid pressure source, there are concerns relating to cross-contamination of the reagents and thus the stability of the reagents. For example, in an automated DNA synthesis instrument, there are a number of reagents including amidites, acetonitrile, tetrazole, oxidizer reagents, etc. which are held in containers. These containers are pressurized to force a small quantity of each reagent to be dispensed from the containers in a specific sequence. In the past, to simplify the instrument configuration, a single gas source was used to pressurize the containers via a manifold and pressure conduits connected to the containers. It has been found that the vapors of the reagents diffuse through the pressure conduits from the containers back to the manifold and the vapors may further diffuse to other containers. The chemical stability of the reagents is extremely sensitive to moisture or contamination by other reagents. For example, acetonitrile is extremely hydrophilic. Moisture vapor from the oxidizer reagent can negatively affect the chemical stability of the acetonitrile. This is undesirable as it affects the reliability of the synthesis product, not to mention the waste associated with replacing the deteriorated reagents which are relatively expensive, as well as prematurely replacing good reagents left in the instrument after a period of time just in case they may have deteriorated.